Habitat for Humanity ReStore always has carpet squares out of old office spaces. Last wek I bought a pile of 3'x3' squares, enough to insulate two blinds for $45. Its short carpet and well padded. I tested them and a 9/16 staple will hang them on the wall. Should fit the bill.

Habitat for Humanity ReStore always has carpet squares out of old office spaces. Last wek I bought a pile of 3'x3' squares, enough to insulate two blinds for $45. Its short carpet and well padded. I tested them and a 9/16 staple will hang them on the wall. Should fit the bill.

Closed cell spray foam insulation. Waterproof, no insect problems, no condensation, and your body heat will keep it pretty nice in there a heater will run you out of there. Any kind of insulation board bugs will get behind.

The insulation board glued to the walls and use a good caulking around the exposed edges will seal it off. Make sure exterior is sealed off at all areas also.The carpet on walls also glue on and seal edges.